An infrared radiation thermometer collects the infrared thermal radiation energy of a target via its optical system, the energy is directly or indirectly (via the optical fiber transmission) focused on an infrared temperature measuring sensor and is converted into electric signals, and the electric signals are subjected to subsequent circuit processing so as to display the measuring temperature and output corresponding electric signals. The optical system can have the following forms:
A. the optical system is only provided with an objective incapable of being focused and is generally added with laser beams in the indicating measurement direction. Such structure is the simplest and is mainly applied to easy low-medium-high temperature infrared radiation thermometers;
B. the optical system is provided with an eyepiece and the objective which cannot be focused. The structure is also simple. For instance, the IR-HS portable infrared radiation thermometer produced by Japan CHINO Company is adopted;
C. the objective can be focused at the front end of the probe and the eyepiece cannot be focused at the back end of the probe. Such structure is frequently used in the products with medium temperature and high temperature. For instance, the Marathon series of infrared radiation thermometers produced by U.S. Raytek company, the SR and the Modline 3 series of infrared radiation thermometers produced by U.S. IRCON company;
D. the objective can be focused at the front end of the probe and the eyepiece can be focused at the back end of the probe. Such structure is usually applied to high-end products, which is similar to the technology associated with the invention. For instance, the TR-630 produced by British LAND company and Japan MINOLTA company, the IR-AH portable infrared radiation thermometer and partial IR-CA series of infrared thermometers produced by Japan CHINO company, and the XTIR-F series of optical fiber infrared thermometers produced by Shanghai cooperative physical institute;
E. the objective can be focused at the back end of the probe, but the eyepiece at the back of the probe cannot be focused. Such structure is relatively complicated and is novel as well, which can be seen in few high-end products and is similar to the technology associated with the invention. For instance, the SYSTEM 4(S4 abbr.) series of fixed-type infrared radiation thermometers produced by British LAND company and Modline 5 series of integrated infrared radiation thermometers produced by U.S. IRCON company.
Deficiencies and disadvantages of available technologies:
a. the objective is fixed so that the measured image distance cannot be regulated according to the variation of the measured object distance, resulting in lower resolution of optical focusing;
b. the accurate and effective measured part of the target cannot be aimed, observed and judged due to lack of the eyepiece; when the target turns red due to the bright environmental lighting or the high target temperature, the aiming effect of pointing by the laser red dot on the measured plane can be lost for this reason;
c. the eyepiece cannot be focused, so the observation effect on the aiming circle (or aiming cross) and target imaging on the dividing plane would be influenced due to the vision difference of operators and the optimal optical objective focusing measuring effect also cannot be achieved;
d. the focusing operation of the objective at the front end of the probe would be influenced by assembling and using of an air purging device and a water cooled jacket;
e. the focusing operation part and the movable gap are exposed, which can be easily polluted and permeated by oil steam and dust on the industrial site when used on-line for long term, as a result, instruments are easy to go wrong and the using of the instruments is influenced; additionally, focusing operation part and the movable gap are also inconvenient to wash in maintaining and cleaning process;
f. the objective cannot be locked or is inconvenient to lock and is easy to forgot after being focused, so the measuring result may be changed due to the vibration influence of the workpiece which is subjected to temperature measurement when the objective is used on-line;
g. the existing high-end technology of carrying out focusing operation on the objective at the back of the probe has complex design structure and also has the defects that the eyepiece cannot be focused and the like. For instance, the SYSTEM 4(S4 abbr.) series of fixed-type infrared radiation thermometers produced by British LAND company, wherein the front end of the probe is sealed and the objective is moved and focused by revolving an objective focusing ring at the back end; the components of a focusing transmission structure comprise a casting frame, a focusing ring, a gear set, a transmission connecting rod, a spring, threads, etc; and except the damping effect of the spring, the eyepiece cannot be focused if no focusing locking device is provided.
According to the Modline 5 series of integrated infrared radiation thermometers produced by U.S. IRCON company, the objective is sealed and fixed at the front end of the probe, the focusing operation of the objective is realized by revolving a second-half casing of the probe and making an internal core take the integral linear displacement, an external cable connecting pedestal is fixed on a first-half casing, and a plurality of cable connecting wires inside would be pulled forward and backward in the focusing process; the focusing locking operation is realized by twisting a king bolt of which a base is fixed on the first-half casing of the probe to support the rotary second-half casing of the probe; the requirement on the machining fit precision of the rotary casing is high; and the eyepiece cannot be focused.